CHEMISTRY GLOSSARY
substitution → supstitucija
Substitution (substitution reaction) is a reaction in which an atom or fragment within a molecule is replaced with another atom or a fragment.
surface tension → površinska napetost
Surface tension (σ) is a property of liquids arising from unbalanced molecular cohesive forces at or near the surface, as a result of which the surface tends to contract and has properties resembling those of a stretched elastic membrane. As a result of which the surface tends to contract and has properties resembling those of a stretched elastic membrane.
Gratzel solar cell → Gratzelova sunčeva ćelija
Grätzel solar cell is photoelectrochemical cell, developed by Michael Grätzel and collaborators, simulates some characteristics of the natural solar cell, which enables photosynthesis take place. In natural solar cell the chlorophyll molecules absorb light (most strongly in the red and blue parts of the spectrum, leaving the green light to be reflected). The absorbed energy is sufficient to knock an electron from the excited chlorophyll. In the further transport of electron, other molecules are involved, which take the electron away from chlorophyll. In Grätzel cell, the tasks of charge-carrier generation and transport are also assigned to different species.
His device consists of an array of nanometre-sized crystallites of the semiconductor titanium dioxide, welded together and coated with light-sensitive molecules that can transfer electrons to the semiconductor particles when they absorb photons. So, light-sensitive molecules play a role equivalent to chlorophyll in photosynthesis. In Grätzel cell, the light-sensitive molecule is a ruthenium ion bound to organic bipyridine molecules, which absorb light strongly in the visible range; titanium dioxide nanocrystals carry the received photoexcited electrons away from electron donors. On the other hand, a donor molecule must get back an electron, so that it can absorb another photon. So, this assembly is immersed in a liquid electrolyte containing molecular species (dissolved iodine molecules) that can pick up an electron from an electrode immersed in the solution and ferry it to the donor molecule. These cells can convert sunlight with efficiency of 10 % in direct sunlight and they are even more efficient in diffuse daylight.
halogens → halogeni elementi
Halogens are the elements fluorine (F) chlorine (Cl), bromine (Br), iodine (I), and astatine (At). They are non-metals, and make up part of the 17 group in the periodic table. Compounds of these elements are called halogenides or halides.
The halogens all have a strong unpleasant odour and will burn flesh. They do not dissolve well in water. The five elements are strongly electronegative. They are oxidising agents, with fluorine being the strongest and astatine being the weakest. They react with most metals and many non-metals.
Halogens form molecules which consist of atoms covalently bonded. With increasing atomic weight there is a gradation in physical properties. For example: Fluorine is a pale green gas of low density. Chlorine is a greenish-yellow gas 1.892 times as dense as fluorine. Bromine is a deep reddish-brown liquid which is three times as dense as water. Iodine is a grayish-black crystalline solid with a metallic appearance. And astatine is a solid with properties which indicate that it is somewhat metallic in character.
temperature → temperatura
Temperature is a measure to the average kinetic energy of its molecules. The SI unit in which thermodynamic temperature is expressed is the kelvin (K).
terminal → terminalni
Terminal in chemistry means: the end of a polymer molecule and a point at which electron connections can easily be made or broken.
unit cell → jedinična ćelija
Unit cell is the smallest fragment of the structure of a solid that by repetition can generate the entire structure.
unsaturated hydrocarbon → nezasićeni ugljikovodik
Unsaturated hydrocarbons are organic compounds containing double (alkenes) or triple (alkynes) bonds in their molecules.
Citing this page:
Generalic, Eni. "Planarna struktura molekule." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.
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